WO2022059159A1

WO2022059159A1 - Signal conversion device and signal conversion method

Info

Publication number: WO2022059159A1
Application number: PCT/JP2020/035385
Authority: WO
Inventors: 暁弘田邉; 利明下羽; 陽一深田; 智暁吉田
Original assignee: 日本電信電話株式会社
Priority date: 2020-09-18
Filing date: 2020-09-18
Publication date: 2022-03-24
Also published as: JPWO2022059159A1; US20230370167A1; JP7372580B2

Abstract

A signal conversion device according to the present invention comprises a conversion unit, a measurement unit and a control unit. The conversion unit performs an FM batch conversion of input signals including multiple carrier signals to generate an FM signal. The measurement unit measures the carrier levels of the multiple carrier signals included in the input signals and also measures the highest frequency of the input signals. The control unit calculates the frequency deviation amount of the input signals as a whole on the basis of the carrier levels measured for the respective ones of the multiple carrier signals. The control unit calculates the center frequency of the FM signal by use of the calculated frequency deviation amount and the measured highest frequency, and controls the conversion unit such that the center frequency of the FM signal generated by the FM batch conversion is equal to the calculated center frequency.

Description

Signal conversion device and signal conversion method

The present invention relates to a signal conversion device and a signal conversion method.

There is an optical transmission device that collectively converts multiple carrier signals by FM (Frequency Modulation) and optical-modulates the converted signals for transmission. The center frequency of the FM signal to be generated is given to this optical transmitter with a fixed value (see, for example, Non-Patent Document 1). By making the center frequency of the FM signal variable within a certain frequency domain, it is possible to control the center frequency from the outside. However, depending on the application, the designer or operator must manually determine the center frequency based on the input signal conditions and experience. The optimum center frequency is not automatically set according to the input signal.

If the carrier signal input to the optical transmitter is always the same, there is no problem even if the center frequency is fixed. However, if the maximum frequency of the input signal becomes high, the signal quality after FM batch conversion deteriorates. Therefore, when the priority is given to maintaining the quality (for example, when the carrier signal is a video signal and it is necessary to ensure that the video can be viewed), there arises a problem that the transmission distance becomes short.

FIG. 8 is a configuration diagram showing the internal structure of a conventional optical transmitter. In signal generation by FM batch conversion, an appropriate center frequency of (c) is determined for the input signal c. However, in the optical transmission device using the current FM batch conversion, a fixed value OF is given as the center frequency of (c) regardless of the frequency of the input signal c. For example, it is assumed that the input signal c1 shown in (a1) is a broadcast signal using the IF (Intermediate Frequency) band of right-handed circular polarization of satellite broadcasting. The broadcast signal includes carrier signals of a plurality of different frequencies (carriers). Initially, the fixed value OF is the center frequency of (c1) of the FM batch conversion signal shown in (b1). That is, the fixed value OF is the center frequency of (c1) in which 2.1 GHz, which is the IF band of the right-handed circular polarization of satellite broadcasting, is matched to the highest frequency. In addition to this, when a new broadcast signal using the left-handed circular polarization of satellite broadcasting is to be transmitted, the maximum frequency of the input signal c2 is 3.2 GHz, which is the IF band of the left-handed circular polarization, as shown in (a2). It rises to the belt. Therefore, as shown in (b2), the center frequency of (c2) of the FM batch conversion signal should be larger than the fixed value OF. However, since the center frequency is fixed, the center frequency of (c2)'of the FM batch conversion signal generated for the input signal c2 remains OF. In this case, the low frequency region of the signal spread around the OF is folded back (reference numeral e) and superimposed on the FM signal, which becomes noise and the signal is deteriorated.

As described above, in the signal after FM batch conversion, if the original center frequency of (c) is larger than the fixed value center frequency OF, the low frequency component is folded back and the signal quality is deteriorated. In order to solve this, the center frequency of the signal after FM batch conversion must be shifted to the high frequency region to obtain the original center frequency. However, in the prior art, the center frequency is fixed, so if different carrier signals are input signals, prepare a separate optical transmitter that can set the center frequency adapted to each input signal, or manually from the outside. The settings should allow the optical transmitter to change the center frequency. When changing manually, only a person who has a good understanding of the characteristics of the input signal can set an appropriate value.

In view of the above circumstances, it is an object of the present invention to provide a signal conversion device and a signal conversion method capable of suppressing deterioration of a generated FM signal even when the frequency of a signal to be subjected to FM batch conversion is variable. It is supposed to be.

One aspect of the present invention is a conversion unit that collectively converts an input signal including a plurality of carrier signals into an FM signal to generate an FM signal, a carrier level of the plurality of the carrier signals included in the input signal, and the input signal. The frequency shift amount of the entire input signal is calculated based on the carrier level measured for each of the plurality of carrier signals and the measuring unit for measuring the maximum frequency of the above, and the calculated frequency shift amount and measurement are performed. A control unit that calculates the center frequency of the FM signal using the calculated maximum frequency and controls the conversion unit so that the center frequency of the FM signal generated by the FM batch conversion becomes the calculated center frequency. , Is a signal conversion device.

One aspect of the present invention is a conversion step in which a conversion unit performs FM batch conversion of an input signal including a plurality of carrier signals to generate an FM signal, and a measurement unit comprises a plurality of the carrier signals included in the input signal. The measurement step for measuring the carrier level of the input signal and the maximum frequency of the input signal, and the control unit calculates the frequency shift amount of the entire input signal based on the carrier level measured for each of the plurality of carrier signals. Then, the center frequency of the FM signal is calculated using the calculated frequency shift amount and the measured maximum frequency, and the center frequency of the FM signal generated by the FM batch conversion is calculated with the calculated center frequency. It is a signal conversion method including a control step for controlling the conversion unit so as to be.

According to the present invention, it is possible to suppress deterioration of the generated FM signal even when the frequency of the signal to be FM batch converted is variable.

It is a block diagram of the optical transmission apparatus by one Embodiment of this invention. It is a block diagram of the FM batch conversion part by the same embodiment. It is a figure for demonstrating the measurement method of the electric signal by the same embodiment. It is a figure which shows the example of the frequency offset amount peculiar to the apparatus by the same embodiment. It is a block diagram of the optical transmission apparatus by the same embodiment. It is a block diagram of the FM batch conversion part by the same embodiment. It is a figure which shows the hardware composition of the control part by the same embodiment. It is a block diagram of the conventional optical transmission device.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The network transmission system transmits the carrier signal by FM batch conversion technology and optical modulation. The carrier signal is an electric signal such as an RF video signal. The network transmission system has an optical transmission device that generates an optical signal to be transmitted. The optical transmission device has a signal conversion unit that performs FM batch conversion of a plurality of carrier signals to generate an FM batch conversion signal, and converts the generated FM batch conversion signal into an optical signal. The signal conversion unit of the present embodiment inputs an electric signal and measures and analyzes the characteristics of the input electric signal. The signal conversion unit determines an appropriate center frequency of the FM signal using the measurement / analysis result, and dynamically controls the center frequency when performing FM batch conversion. This makes it possible to suppress signal deterioration caused by transmission of optical signals as much as possible.

FIG. 1 is a configuration diagram of an optical transmission device 1 according to an embodiment of the present invention. The optical transmission device 1 is an example of a signal conversion device that performs FM batch conversion on an electric signal to generate an FM batch conversion signal. The optical transmission device 1 includes an electric signal input IF (interface) 11, a signal conversion unit 12, an electric / optical conversion unit 13, and an optical signal output IF 14. The signal conversion unit 12 includes a branch unit 21, an amplification unit 22, an amplification unit 23, a measurement unit 24, a control unit 25, an FM batch conversion unit 26, and a storage unit 27. The signal conversion unit 12 may or may not have the amplification unit 22 and may not have the amplification unit 23. The storage unit 27 may be provided in the measurement unit 24 or may be provided in the control unit 25.

The electric signal input IF 11 inputs an electric signal and outputs the input electric signal to the branch portion 21. The electrical signal includes one or more carrier signals. The frequency of each carrier signal is different. The electrical signal may include signals in a plurality of frequency domains, each including one or more carrier signals. For example, the electric signal may be a plurality of carrier signals included in the IF band (frequency domain) of CS right-handed circular polarization, or may be a plurality of carrier signals included in the IF band (frequency domain) of CS left-handed circular polarization. , Carrier signals in both of these frequency domains may be included.

The branch portion 21 branches the electric signal input from the electric signal input IF 11 into two. The branching unit 21 outputs one of the branched electric signals to the measuring unit 24, and outputs the other electric signal to the FM batch conversion unit 26. The amplification unit 22 amplifies the electric signal output by the branch unit 21 to the measurement unit 24. The amplification unit 23 amplifies the electric signal output by the branch unit 21 to the FM batch conversion unit 26.

The measuring unit 24 inputs the electric signal output by the branching unit 21, and measures the data necessary for deriving the center frequency with the input electric signal as the measurement target. The items to be measured are (item 1) the level of each carrier signal included in the input electric signal, and (item 2) the maximum frequency f _max of the input electric signal. The measurement unit 24 outputs measurement data indicating the results of measuring these items to the control unit 25.

The control unit 25 receives measurement data from the measurement unit 24. The control unit 25 calculates the center frequency of (c) of the FM batch conversion signal generated by the FM batch conversion unit 26 using the measurement data. The control unit 25 notifies the FM batch conversion unit 26 of the calculated center frequency of (c) by a control signal. The calculation of the center frequency of (c) is based on Carson's law (see, for example, Reference 1), but it is necessary to satisfy that the FM modulation degree is sufficiently smaller than 1 (see, for example, Reference 2).

(Reference 1) Institute of Electronics, Information and Communication Engineers Knowledge Base, 5 groups Communication / Broadcasting 8 editions Broadcasting / CATV Chapter 2 Modulation method and transmission, pp.11-12, [online], [Search on August 19, 2020], Internet <http://www.ieice-hbkb.org/files/05/05gun_08hen_02.pdf>

(Reference 2) Nao Yoshinaga, Toshiaki Shimoha, Naohiko Yuki, Satoshi Ikeda, "Transmission method of BS / CS 110 ° signal by FM batch conversion method (1) -System design-", IEICE 2007 Society Conference

The FM batch conversion unit 26 inputs the electric signal output from the branch unit 21, and converts the input electric signal into an FM batch conversion signal having a center frequency notified by the control signal from the control unit 25. The FM batch conversion unit 26 outputs the converted FM batch conversion signal to the electric / optical conversion unit 13. The storage unit 27 stores various set values.

The electric / optical conversion unit 13 converts the FM batch conversion signal input from the FM batch conversion unit 26 from an electric signal to an optical signal. The electric / optical conversion unit 13 outputs the converted optical signal to the optical signal output IF 14. The optical signal output IF 14 outputs an optical signal input from the electric / optical conversion unit 13 to the outside.

According to the above configuration, when the input signal c1 shown in (a1) is input to the optical transmission device 1, the signal conversion unit 12 generates the FM batch conversion signal SG1 having the center frequency of (c1) shown in (b1). Further, it is assumed that the input signal c2 shown in (a2) is input to the optical transmission device 1. The input signal c2 differs from the input signal c1 in at least one of the highest frequency and the lowest frequency. In this case, the signal conversion unit 12 generates the FM batch conversion signal SG2 having the center frequency of (c2) ≠ of (c1) shown in (b2).

FIG. 2 is a configuration diagram of the FM batch conversion unit 30. The FM batch conversion unit 30 is used as the FM batch conversion unit 26 shown in FIG. The FM batch conversion unit 30 includes an optical modulation control unit 31, a bias tee 32, an optical modulation unit 33, an electricity generation unit 34, an optical modulation unit 35, an optical combine wave unit 36, and an optical heterodyne detection unit 37. Be prepared. The FM batch conversion unit 30 may further include a frequency stabilizing unit 38.

The optical modulation control unit 31 receives a control signal from the control unit 25, and acquires center frequency information from the received control signal. The optical modulation control unit 31 controls the current value of the current applied by the bias tee 32 and the current value of the electricity generated by the electricity generating unit 34 based on the center frequency indicated by the acquired information. As a result, the center frequency of the FM batch conversion signal output via the optical combiner unit 36 and the optical heterodyne detection unit 37 is controlled to be the value of the center frequency calculated by the control unit 25.

Specifically, the optical modulation control unit 31 controls the bias tee 32 so that the frequency of the optical signal output from the optical modulation unit 33 becomes f _L [GHz], and the light output from the optical modulation unit 35. The electric generator 34 is controlled so that the frequency of the signal becomes f _S [GHz]. The optical modulation control unit 31 sets f _L and f _S so that the center frequency of the FM batch conversion signal of the frequency | f _L − f _S | output by the optical heterodyne detection unit 37 becomes the center frequency acquired from the control signal. decide. For example, the optical modulation control unit 31 implements an arithmetic algorithm or a table for determining a control value for the bias tee 32 and a control value for the optical modulation unit 35 according to the center frequency.

The bias tee 32 is an example of a DC (direct current) application unit. The bias tee 32 inserts a DC current or a DC voltage into the high frequency circuit. The FM batch conversion unit 30 applies a DC current or a DC voltage to the electric signal branched by the branch unit 21 after the output from the electric signal input IF 11 based on the control from the optical modulation control unit 31. The bias tee 32 outputs an input signal to which a DC current or a DC voltage is applied to the optical modulation unit 33.

The optical modulation unit 33 is, for example, a laser diode (LD). The optical modulation unit 33 oscillates the laser beam by injecting a DC current or a current of an input signal to which a DC voltage is applied into the LD by the bias tee 32. As a result, the optical modulation unit 33 intensity-modulates the input signal, converts it into an optical signal having a frequency f _L , and outputs the input signal to the optical combiner unit 36.

The electricity generation unit 34 generates DC electricity having a current value based on the control from the optical modulation control unit 31, and outputs the generated electricity to the optical modulation unit 35. The optical modulation unit 35 is, for example, an LD. The light modulation unit 35 oscillates a laser beam having a frequency _fS by injecting the electricity generated by the electricity generation unit 34 into the LD.

The optical combiner 36 combines an optical signal having a frequency f _L generated by the optical modulation unit 33 with a laser beam having a frequency f _S generated by the optical modulation unit 35. The optical combiner 36 outputs the optical signal generated by the combiner to the optical heterodyne detection unit 37.

The optical heterodyne detection unit 37 is, for example, a photodiode (PD). The optical heterodyne detection unit 37 performs optical heterodyne detection on the optical signal output by the optical combiner unit 36 to generate an FM batch conversion signal of electricity having a frequency | f _L -f _S | [GHz].

The frequency stabilizing unit 38 is, for example, a frequency divider or a multiplier. When the frequency band of the FM batch conversion signal generated by the optical heterodyne detection unit 37 is different from the target frequency, the frequency stabilizing unit 38 converts the frequency of the FM batch conversion signal to the target frequency.

FIG. 3 is a diagram for explaining a method of measuring an electric signal in the measuring unit 24. The measurement of the electric signal is performed by the following procedures A1 to A3.

(Procedure A1) The measurement minimum frequency MF _min , the measurement maximum frequency MF _max , and the measurement frequency width MF _width for determining the measurement width of the input signal are determined in advance. The minimum measurement frequency MF _min corresponds to the frequency at which the measurement starts, and the maximum measurement frequency MF _max corresponds to the frequency at which the measurement ends. The optical transmitter 1 fixedly holds the values of the measurement minimum frequency MF _min , the measurement maximum frequency MF _max , and the measurement frequency width MF _width in the storage unit 27 or the measurement unit 24.

The frequency band that can be amplified is determined by the characteristics of the amplification unit 22 and the amplification unit 23. Therefore, the optical transmission device 1 may fix the maximum value of the frequency that can be amplified by the amplification unit 22 and the amplification unit 23 as the measurement maximum frequency MF _max in the storage unit 27 or the measurement unit 24. Alternatively, the maximum measurement frequency MF _max may be set in the storage unit 27 or the measurement unit 24 from the outside. The measured frequency width MF _width is the same as the carrier width of the input signal, that is, the frequency width of the carrier signal included in the input signal.

When there are a plurality of types of carrier signals, the values of the measured minimum frequency MF _min , the measured maximum frequency MF _max , and the measured frequency width MF _width are set for each carrier signal type. An example of a carrier signal type is a broadcast signal using right-handed circular polarization of satellite broadcasting, a broadcasting signal using left-handed circular polarization of satellite broadcasting, and the like.

(Procedure A2) Before measuring the carrier level, which is the level of the carrier signal, a level threshold C _min is set. Similar to the above, the optical transmission device 1 may hold the threshold value C _min fixedly in the storage unit 27 or the measurement unit 24, or may set the threshold value C _min in the storage unit 27 or the measurement unit 24 from the outside. good. Further, when there are a plurality of types of carrier signals, a value of the threshold value C _min may be set for each carrier signal type.

(Procedure A3) The measuring unit 24 starts measuring the electric signal from the measurement minimum frequency MF _min . The measuring unit 24 slides the measurement frequency by the measurement frequency width MF _width , and the carrier level _ci (f) of each of the n measurement frequencies included in the measurement frequency region from the measurement minimum frequency MF _min to the measurement maximum frequency MF _max . ) Is measured. Note that i indicates a carrier number (i = 1, 2, ..., N). When the measuring unit 24 determines that _ci (f) <C _min , the measured value is discarded, but the measured frequency value at the time of discarding is recorded in the storage unit 27 or the measuring unit 24. However, the measuring unit 24 does not record when _ci (f) <C _min is continuous, that is, when _ci (f) <C _min is also obtained in the previous measurement. The measurement unit 24 ends the measurement when the measurement frequency exceeds the measurement maximum frequency MF _max , and determines that the measurement frequency value at which _ci (f) <C _min at that time is the maximum frequency f _max . ..

In FIG. 3, the measuring unit 24 has a carrier level c _i (f) (i = 1, 2, ..., N) and a maximum frequency f _max for each frequency (carrier) in each of the measurement frequency regions a and b. Ask for. The measurement frequency region a is a region having a lower frequency than the measurement frequency region b.

As the above procedure A1, first, the measurement minimum frequency MF _min _a, the measurement maximum frequency MF _max _a, and the measurement frequency width MF _width _a in the measurement frequency region a are determined. Similarly, the measurement minimum frequency MF _min _b and the measurement maximum frequency Mf _max _b in the measurement frequency region b and the measurement frequency width MF _width _b are defined. In FIG. 3, the measurement maximum frequency MF _max _a and the measurement minimum frequency MF _min _b are the same, and the measurement frequency region a and the measurement frequency region b are adjacent to each other. However, the measurement frequency region a and the measurement frequency region b may not be adjacent to each other, and the measurement maximum frequency MF _max _a and the measurement minimum frequency MF _min _b may be different values.

Further, as the procedure A2, a carrier level threshold value C _min _a used in the measurement frequency region a and a carrier level threshold value C _min _b used in the measurement frequency region b are determined. The threshold C _min _a and the threshold C _min _b may be the same or different. The storage unit 27 or the measurement unit 24 has a measurement minimum frequency MF _min _a, a measurement maximum frequency MF _max _a, a measurement frequency width MF _width _a, and a carrier level threshold C _min _a in the measurement frequency region a, and a measurement frequency region b. The measurement minimum frequency MF _min _b, the measurement maximum frequency MF _max _b, the measurement frequency width MF _width _b, and the carrier level threshold C _min _b are stored.

As the procedure A3, the measuring unit 24 starts the measurement of the electric signal from the measurement minimum frequency MF _min _a, and sequentially increments the frequency by the measurement frequency width MF _width _a, and the frequencies c ₁ (f) and c ₂ (f). ,… Measure the carrier level. The measuring unit 24 records the frequency f _x when the carrier level first becomes less than the threshold C _min _a after the carrier level becomes the threshold C _min _a or more. The frequency f _x corresponds to the maximum frequency f _max before measuring the measurement frequency region b. Even after recording, the measuring unit 24 continues measuring the carrier level until the maximum measured frequency MF _{max_a} is reached.

Subsequently, the measurement unit 24 starts measuring the electric signal from the minimum measurement frequency MF _min _b, and sequentially increments the frequency by the measurement frequency width MF _width _b, and the frequencies c ₁ (f), c ₂ (f),. ... measure the carrier level. The measuring unit 24 records the frequency f _y (> frequency f _x ) when the carrier level first becomes less than the threshold C _min _b after the carrier level becomes the threshold C _min _b or more. Even after recording, the measuring unit 24 continues measuring the carrier level until the maximum measured frequency MF _{max_b} is reached. After the measurement is completed, the measurement unit 24 sets the value of the maximum frequency f _y such that _ci (f) ≧ C _min _b in the measurement frequency region b as the maximum frequency f _max .

Next, a method of calculating the center frequency of (c) in the control unit 25 will be described. The control unit 25 calculates the center frequency of (c) by the following procedures B1 to B3.

(Procedure B1) The control unit 25 calculates the frequency deviation amount _di (f) of each carrier signal using the measured carrier level _ci (f). The calculation formula of the frequency deviation amount _di (f) is determined by the characteristics of the amplification unit 22 and the amplification unit 23 of the electric signal in the optical transmission device 1. In other words, since this calculation formula differs for each device, no specific formula will be mentioned here. The control unit 25 holds this calculation formula inside and performs a calculation based on this calculation formula.

FIG. 4 is a diagram showing an example of the frequency offset amount _di (f) peculiar to the device. The control unit 25 calculates the frequency deviation amount _di (f) by the function F ( _fi , _ci ) using the frequency fi of the _i -th carrier signal and the input level c _i as parameters. The function F ( _fi , _ci ) is unique to each device. In FIG. 4, the relationship between the carrier frequency _fi [ _MHx ] in the frequency measurement region a and the frequency deviation amount di (f) [MHz] calculated by the function Fa (fi, _ci ₎ , and the frequency. The relationship between the carrier frequency _fi [MHx] in the measurement region b and the frequency deviation amount _di (f) [MHz] calculated by the function Fb (fi, c _i ₎ is shown.

(Procedure B2) The control unit 25 uses the value of the frequency deviation amount _di (f) calculated in (1) to obtain the frequency deviation amount (total deviation) offset of the entire input signal by the equation (1). calculate.

(Procedure B3) Based on Carson's law, the control unit 25 uses the frequency deviation amount dtotal calculated by the equation (1) and the value of the maximum frequency f _max indicated by the measurement data according to the following equation (2). The center frequency of (c) is approximately calculated.

of (c) = dtotal + f _max ... (2)

The Carson's law is the following equation (3) for obtaining the frequency bandwidth W from the frequency deviation amount dtotal and the maximum frequency f _max .

W = 2 (dtotal + f _max ) ... (3)

The center frequency is given by half W / 2 of the frequency bandwidth W. However, it is a condition that the above equations (2) and (3) can be applied that the modulation index is less than 1 and the energy is concentrated by 95% or more.

FIG. 5 shows another configuration example of the optical transmitter. FIG. 5 is a block diagram of the optical transmission device 1a. In FIG. 5, the same parts as those of the optical transmission device 1 shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. The difference between the optical transmission device 1a and the optical transmission device 1 shown in FIG. 1 is that the optical transmission device 1a includes a signal conversion unit 12a instead of the signal conversion unit 12. The signal conversion unit 12a includes a measurement unit 24a, a control unit 25a, and an FM batch conversion unit 26a. The signal conversion unit 12a may further include a storage unit 27.

The measuring unit 24a inputs an electric signal from the electric signal input IF11, and performs the same measurement as the measuring unit 24 on the input electric signal. The measurement unit 24a outputs the measurement data and the electric signal to the control unit 25a.

The control unit 25a uses the measurement data received from the measurement unit 24a to calculate the center frequency of (c) in the same manner as the control unit 25. The control unit 25a outputs a control signal for notifying the calculated center frequency of (c) and an electric signal to the FM batch conversion unit 26a.

The FM batch conversion unit 26a operates in the same manner as the FM batch conversion unit 26, except that a control signal and an electric signal are input from the control unit 25a. That is, the FM batch conversion unit 26a converts the input electric signal into an FM batch conversion signal having a central frequency notified by the control signal, and outputs the converted FM batch conversion signal to the electric / optical conversion unit 13. When the FM batch conversion unit 30 shown in FIG. 2 is used as the FM batch conversion unit 26a, the optical modulation control unit 31 receives a control signal from the control unit 25a, and the bias tee 32 inputs an electric signal from the control unit 25a. ..

Further, the FM batch conversion unit 40 shown in FIG. 6 may be used as the FM batch conversion unit 26 of the optical transmission device 1 or the FM batch conversion unit 26a of the optical transmission device 1a. The FM batch conversion unit 40 inputs a wide band signal of 1 GHz or more.

FIG. 6 is a diagram showing the configuration of the FM batch conversion unit 40. In the figure, the same parts as those of the FM batch conversion unit 30 shown in FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted. The FM batch conversion unit 40 includes an optical modulation control unit 41, a branch unit 42, an antiphase branch unit 43, a bias tee 44, an optical modulation unit 45, an optical phase modulation unit 46, a bias tee 47, and optical light. It includes a modulation unit 48, an optical combiner unit 36, and an optical heterodyne detection unit 37. The FM batch conversion unit 40 may further include an amplification unit 49 and may further include a frequency stabilization unit 38.

The optical modulation control unit 41 receives a control signal from the control unit 25 of the optical transmission device 1 or the control unit 25a of the optical transmission device 1a, and acquires center frequency information from the received control signal. The optical modulation control unit 41 controls the current value of the current applied by each of the bias tee 44 and the bias tee 47 based on the center frequency indicated by the acquired information. The optical modulation control unit 41 controls the bias tee 44 so that the frequency of the optical signal output from the optical phase modulation unit 46 becomes f _L [GHz], and the frequency of the optical signal output from the optical modulation unit 48 becomes. The bias tee 47 is controlled so as to be f _S [GHz]. The optical modulation control unit 41 sets f _L and f _S so that the center frequency of the FM batch conversion signal of the frequency | f _L − f _S | output by the optical heterodyne detection unit 37 becomes the center frequency acquired from the control signal. decide. The optical modulation control unit 41 implements an arithmetic algorithm or a table for determining control values for each of the bias tee 44 and the bias tee 47 according to the center frequency.

The FM batch conversion unit 40 is the electric signal branched by the branching unit 21 after the output from the electric signal input IF 11 of the optical transmission device 1, or the measurement unit 24a and the control after the output from the electric signal input IF 11 of the optical transmission device 1a. An electric signal is input via the unit 25a. When the electric signal input by the FM batch conversion unit 40 contains a wide band component fb (1 GHz or more), the branch unit 42 separates the wide band component fb from this input signal. The branch section 42 outputs the input signal of the band fa excluding the wide band component to the antiphase branch section 43, and outputs the input signal of the wide band component fb to the optical phase modulation section 46. This is because the output of the optical modulation unit 45 is not stable (charping), so that the wideband component is branched to perform phase modulation. The amplification unit 49 amplifies the input signal of the frequency fb output by the branch unit 42 to the optical phase modulation unit 46.

The anti-phase branching unit 43 generates an electric signal of an anti-phase component of the input signal of the band fa input from the branching unit 42, and branches the generated electric signal into two. The anti-phase branching unit 43 outputs one of the branched electric signals to the optical modulation unit 45, and outputs the other branched electric signal to the optical modulation unit 48. The electric signal of the anti-phase component is used to suppress the residue of the intensity modulation component in the FM batch conversion signal.

The bias tee 44 is an example of a DC application unit, and has the same configuration as the bias tee 32. The bias tee 44 applies a DC current or a DC voltage to the electric signal output by the antiphase branching unit 43 to the optical modulation unit 45 based on the control from the optical modulation control unit 41.

The optical modulation unit 45 is, for example, an LD. The optical modulation unit 45 oscillates laser light by injecting a DC current or an electric signal current to which a DC voltage is applied into the LD by the bias tee 44. As a result, the optical modulation unit 45 intensity-modulates the electric signal, converts it into an optical signal having a frequency f _L , and outputs the electric signal to the optical phase modulation unit 46.

The optical phase modulation unit 46 modulates the phase of the optical signal output from the optical modulation unit 45 with the input signal of the frequency fb output by the branch unit 42, and generates an optical signal having a frequency f _L. The optical phase modulation unit 46 outputs the generated optical signal of frequency f _L to the optical combine unit 36.

The bias tee 47 is an example of a DC application unit, and has the same configuration as the bias tee 32. The bias tee 47 applies a DC current or a DC voltage to the electric signal output by the antiphase branching unit 43 to the optical modulation unit 45 based on the control from the optical modulation control unit 41.

The optical modulation unit 48 is, for example, an LD. The optical modulation unit 48 oscillates the laser beam by injecting a DC current or an electric signal current to which a DC voltage is applied into the LD by the bias tee 47. As a result, the optical modulation unit 48 intensity-modulates the electric signal, converts it into an optical signal having a frequency _fS , and outputs the converted optical signal to the optical combine unit 36.

The optical combiner 36 combines an optical signal having a frequency f _L generated by the optical phase modulation unit 46 with a laser beam having a frequency f _S generated by the optical modulation unit 48, and the light generated by the combined wave is combined. The signal is output to the optical heterodyne detection unit 37.

By applying the

optical transmission devices

1 and 1a of the above-described embodiment to a transmission network using the FM batch conversion method, even if the maximum frequency of the input signal becomes high, the device can be replaced or the device has specialized knowledge. An appropriate FM signal can be generated without changing the center frequency setting.

On the contrary, even when the maximum frequency of the input signal becomes low, there are the following advantages. That is, in the situation where the

optical transmitters

1 and 1a are used at the center frequency with the maximum frequency set to the 3.2 GHz band, if the maximum frequency is changed to the 2.1 GHz band, the center frequency originally required is not generated. The signal is generated at a higher value than. Therefore, by setting the

optical transmitters

1 and 1a to the center frequency matched to the 2.1 GHz band, the influence of wavelength dispersion in the optical signal transmission path can be reduced, and the transmission distance can be extended more than before. Become. For example, when the input signal is a video signal, the transmission distance is extended, so that the video signal can be delivered to an area where the video signal could not be normally received and the video could not be viewed.

The control unit 25 of the optical transmission device 1 and the control unit 25a of the optical transmission device 1a include a CPU (Central Processing Unit), a memory, an auxiliary storage device, and the like connected by a bus, and execute a program to execute the above-described embodiment. May realize the function in. All or part of the functions of the control unit 25 of the optical transmission device 1 and the control unit 25a of the optical transmission device 1a are ASIC (Application Specific Integrated Circuit), PLD (Programmable Logic Device), FPGA (Field Programmable Gate Array). ) And other hardware may be used. The program of the control unit 25 of the optical transmission device 1 and the program of the control unit 25a of the optical transmission device 1a may be recorded on a computer-readable recording medium. The computer-readable recording medium is, for example, a flexible disk, a magneto-optical disk, a portable medium such as a ROM (Read Only Memory) or a CD-ROM, or a storage device such as a hard disk built in a computer system. The program of the control unit 25 of the optical transmission device 1 and the program of the control unit 25a of the optical transmission device 1a may be transmitted via a telecommunication line.

A hardware configuration example of the control unit 25 of the optical transmission device 1 and the control unit 25a of the optical transmission device 1a will be described. FIG. 7 is a device configuration diagram showing a program of the control unit 25 of the optical transmission device 1 and a hardware configuration example of the control unit 25a of the optical transmission device 1a. The program of the control unit 25 of the optical transmission device 1 and the control unit 25a of the optical transmission device 1a include a processor 71, a storage unit 72, and a communication interface 73. The processor 71, the storage unit 72, and the communication interface 73 are connected to the bus 74. The processor 71 is a central processing unit that performs arithmetic and control. The processor 71 is, for example, a CPU. The storage unit 72 is a ROM, a RAM (RandomAccessMemory), a solid state drive, a hard disk drive, or the like. The processor 71 reads a program from the storage unit 72 and executes it. The storage unit 72 further has a work area for the processor 71 to execute various programs and the like. The communication interface 73 is connected so as to be able to communicate with other functional units.

According to the above-described embodiment, it is possible to set an appropriate center frequency of the FM signal according to the characteristics of the input electric signal, and it is possible to suppress signal deterioration caused by transmission of an optical signal.

The signal conversion device may be configured to include at least the signal conversion unit 12 or the signal conversion unit 12a.

According to the above-described embodiment, the signal conversion device has a conversion unit, a measurement unit, and a control unit. For example, the signal conversion device is the

optical transmission device

1, 1a of the embodiment. The conversion unit performs FM batch conversion of an input signal including a plurality of carrier signals to generate an FM signal. For example, the conversion unit is the FM

batch conversion unit

30 or 40 of the embodiment. The measuring unit measures the carrier level of a plurality of carrier signals included in the input signal and the maximum frequency of the input signal. The control unit calculates the frequency deviation amount of the entire input signal by using the frequency deviation amount calculated based on the carrier level measured for each of the plurality of carrier signals. The control unit calculates the center frequency of the FM signal using the calculated frequency deviation amount and the measured maximum frequency, and the center frequency of the FM signal generated by the FM batch conversion becomes the calculated center frequency. The conversion unit is controlled so as to. For example, the control unit is the control unit 25 and the optical

modulation control units

31, 41 of the embodiment.

The conversion unit may include an application unit, a first optical modulation unit, an electricity generation unit, a second optical modulation unit, an optical combine unit, and a detection unit. The application unit applies a current or voltage to the input signal. For example, the application unit is the bias tee 32 of the embodiment. The first optical modulation unit generates an optical signal whose intensity is modulated by an input signal to which electric power or voltage is applied. For example, the first optical modulation unit is the optical modulation unit 33 of the embodiment. The electricity generator generates electricity. The second optical modulation unit generates light whose intensity is modulated by the electricity generated by the electricity generation unit. For example, the second optical modulation unit is the optical modulation unit 35 of the embodiment. The optical combiner combines the optical signal generated by the first optical modulator and the light generated by the second optical modulator. The detection unit obtains an FM signal by performing optical heterodyne detection of the light combined by the optical combine unit. For example, the detection unit is the optical heterodyne detection unit 37 of the embodiment. The control unit controls the application unit and the electricity generation unit so that the center frequency of the FM signal obtained by the detection unit becomes the calculated center frequency. For example, in the control unit, the application unit and the application unit so that the center frequency of the difference between the frequency of the optical signal output by the first optical modulation unit and the frequency of the light output by the second optical modulation unit becomes the calculated center frequency. Controls the electricity generator.

The conversion unit includes a branch unit, an antiphase branch unit, a first application unit, a first optical modulation unit, an optical phase modulation unit, a second application unit, a second optical modulation unit, and an optical combine unit. And a detection unit may be provided. The branching portion branches the input signal into a first electric signal lower than a predetermined frequency and a second electric signal higher than a predetermined frequency. The anti-phase branching portion branches an electric signal having an anti-phase of the first electric signal into a first anti-phase signal and a second anti-phase signal. The first application unit applies power or voltage to the first antiphase signal. For example, the first application unit is the bias tea 44 of the embodiment. The first optical modulation unit generates an optical signal that is intensity-modulated by the first anti-phase signal to which electric power or voltage is applied. For example, the first optical modulation unit is the optical modulation unit 45 of the embodiment. The optical phase modulation unit phase-modulates the optical signal generated by the first optical modulation unit with the second electric signal. The second application unit applies electric power or voltage to the second antiphase signal. For example, the second application unit is the bias tee 47 of the embodiment. The second optical modulation unit generates an optical signal that is intensity-modulated by the second anti-phase signal to which power or voltage is applied. For example, the second optical modulation unit is the optical modulation unit 48 of the embodiment. The optical combiner unit combines the optical signal phase-modulated by the optical phase modulation unit and the optical signal generated by the second optical modulation unit. The detection unit obtains an FM signal by performing optical heterodyne detection of the optical signal combined with the optical combine unit. For example, the detection unit is the optical heterodyne detection unit 37 of the embodiment. The control unit controls the first application unit and the second application unit so that the center frequency of the FM signal obtained by the detection unit becomes the calculated center frequency. For example, in the control unit, the center frequency of the difference between the frequency of the optical signal phase-modulated by the optical phase modulation unit and the frequency of the optical signal generated by the second optical modulation unit becomes the calculated center frequency. (1) Controls the application unit and the second application unit.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and includes designs and the like within a range that does not deviate from the gist of the present invention.

1 ... Optical transmitter, 1a ... Optical transmitter, 11 ... Electrical signal input IF, 12 ... Signal conversion unit, 12a ... Signal conversion unit, 13 ... Electric / optical conversion unit, 14 ... Optical signal output IF, 21 ... Branch unit , 22 ... Amplification unit, 23 ... Amplification unit, 24 ... Measurement unit, 24a ... Measurement unit, 25 ... Control unit, 25a ... Control unit, 26 ... FM batch conversion unit, 26a ... FM batch conversion unit, 27 ... Storage unit, 30 ... FM batch conversion unit, 31 ... optical modulation control unit, 32 ... bias tea, 33 ... optical modulation unit, 34 ... electricity generation unit, 35 ... optical modulation unit, 36 ... optical combiner unit, 37 ... optical heterodyne detection unit, 38 ... Frequency stabilization unit, 40 ... FM batch conversion unit, 41 ... Optical modulation control unit, 42 ... Branch unit, 43 ... Opposite phase branch unit, 44 ... Biasty, 45 ... Optical modulation unit, 46 ... Optical phase modulation unit , 47 ... bias, 48 ... optical modulation section, 49 ... amplification section, 71 ... processor, 72 ... storage section, 73 ... communication interface, 74 ... bus

Claims

A conversion unit that generates FM signals by batch converting input signals including multiple carrier signals.
A measuring unit that measures the carrier level of a plurality of the carrier signals included in the input signal and the maximum frequency of the input signal.
The frequency deviation amount of the entire input signal is calculated based on the carrier level measured for each of the plurality of carrier signals, and the FM signal is used using the calculated frequency deviation amount and the measured maximum frequency. A control unit that calculates the center frequency of the FM signal and controls the conversion unit so that the center frequency of the FM signal generated by the FM batch conversion becomes the calculated center frequency.
A signal converter.
The conversion unit
An application unit that applies a current or voltage to the input signal,
A first optical modulation unit that generates an optical signal that is intensity-modulated by the input signal to which electric power or voltage is applied, and
The electricity generator that generates electricity and
A second light modulation unit that generates light whose intensity is modulated by the electricity generated by the electricity generation unit, and
An optical combining unit that combines the optical signal generated by the first optical modulation unit and the light generated by the second optical modulation unit.
It is provided with a detection unit that obtains an FM signal by performing optical heterodyne detection of the light that the optical combination unit has combined.
The control unit controls the application unit and the electricity generation unit so that the center frequency of the FM signal obtained by the detection unit becomes the calculated center frequency.
The signal conversion device according to claim 1.
In the control unit, the center frequency of the difference between the frequency of the optical signal output by the first optical modulation unit and the frequency of the light output by the second optical modulation unit is the calculated center frequency. Controls the application unit and the electricity generation unit.
The signal conversion device according to claim 2.
The conversion unit
A branch portion that branches the input signal into a first electric signal lower than a predetermined frequency and a second electric signal higher than the predetermined frequency.
An anti-phase branching portion that branches an electric signal having an anti-phase of the first electric signal into a first anti-phase signal and a second anti-phase signal.
A first application unit that applies power or voltage to the first antiphase signal,
A first optical modulation unit that generates an optical signal intensity-modulated by the first antiphase signal to which electric power or voltage is applied, and a first optical modulation unit.
An optical phase modulation unit that phase-modulates the optical signal generated by the first optical modulation unit with the second electric signal,
A second application unit that applies power or voltage to the second antiphase signal,
A second optical modulation unit that generates an optical signal intensity-modulated by the second antiphase signal to which power or voltage is applied, and a second optical modulation unit.
An optical combiner that combines the optical signal phase-modulated by the optical phase modulator and the optical signal generated by the second optical modulator.
It is provided with a detection unit that obtains an FM signal by performing optical heterodyne detection of the optical signal that the optical combination unit has combined.
The control unit controls the first application unit and the second application unit so that the center frequency of the FM signal obtained by the detection unit becomes the calculated center frequency.
The signal conversion device according to claim 1.
In the control unit, the center frequency of the difference between the frequency of the optical signal phase-modulated by the optical phase modulation unit and the frequency of the optical signal generated by the second optical modulation unit is calculated as the center frequency. The first application unit and the second application unit are controlled so as to be.
The signal conversion device according to claim 4.
A conversion step in which the conversion unit performs FM batch conversion of an input signal including a plurality of carrier signals to generate an FM signal, and
A measurement step in which the measuring unit measures the carrier level of a plurality of the carrier signals included in the input signal and the maximum frequency of the input signal.
The control unit calculates the frequency deviation amount of the entire input signal based on the carrier level measured for each of the plurality of carrier signals, and determines the calculated frequency deviation amount and the measured maximum frequency. A control step that calculates the center frequency of the FM signal using the FM signal and controls the conversion unit so that the center frequency of the FM signal generated by the FM batch conversion becomes the calculated center frequency.
A signal conversion method having.